Problem: Solve for $a$ : $22 = a + 30$
Answer: Subtract $30$ from both sides: $ \begin{eqnarray} \\ \hphantom{22 {- 30}} &\hphantom{=}& \hphantom{a} \\ 22 &=& a + 30 \\ \\ {-30} && {-30} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 22 {- 30} &=& a \\ \end{eqnarray} $ Simplify. $ a = -8$